Integrating Betamax with Test Frameworks

It’s nice to have a way to integrate libraries you use for testing into your testing frameworks. Having considered this, the authors of and contributors to Betamax have included integrations in the package. Betamax comes with integrations for py.test and unittest. (If you need an integration for another framework, please suggest it and send a patch!)

PyTest Integration

New in version 0.5.0.

Changed in version 0.6.0.

When you install Betamax, it now installs two py.test fixtures by default. To use it in your tests you need only follow the instructions on pytest’s documentation. To use the betamax_session fixture for an entire class of tests you would do:

# tests/test_http_integration.py
import pytest

@pytest.mark.usefixtures('betamax_session')
class TestMyHttpClient:
    def test_get(self, betamax_session):
        betamax_session.get('https://httpbin.org/get')

This will generate a cassette name for you, e.g., tests.test_http_integration.TestMyHttpClient.test_get. After running this test you would have a cassette file stored in your cassette library directory named tests.test_http_integration.TestMyHttpClient.test_get.json. To use this fixture at the module level, you need only do

# tests/test_http_integration.py
import pytest

pytest.mark.usefixtures('betamax_session')


class TestMyHttpClient:
    def test_get(self, betamax_session):
        betamax_session.get('https://httpbin.org/get')

class TestMyOtherHttpClient:
    def test_post(self, betamax_session):
        betamax_session.post('https://httpbin.org/post')

If you need to customize the recorder object, however, you can instead use the betamax_recorder fixture:

# tests/test_http_integration.py
import pytest

pytest.mark.usefixtures('betamax_recorder')


class TestMyHttpClient:
    def test_post(self, betamax_recorder):
        betamax_recorder.current_cassette.match_options.add('json-body')
        session = betamax_recorder.session

        session.post('https://httpbin.org/post', json={'foo': 'bar'})

Unittest Integration

New in version 0.5.0.

When writing tests with unittest, a common pattern is to either import unittest.TestCase or subclass that and use that subclass in your tests. When integrating Betamax with your unittest testsuite, you should do the following:

from betamax.fixtures import unittest


class IntegrationTestCase(unittest.BetamaxTestCase):
    # Add the rest of the helper methods you want for your
    # integration tests


class SpecificTestCase(IntegrationTestCase):
    def test_something(self):
        # Test something

The unittest integration provides the following attributes on the test case instance:

  • session the instance of BetamaxTestCase.SESSION_CLASS created for that test.
  • recorder the instance of betamax.Betamax created.

The integration also generates a cassette name from the test case class name and test method. So the cassette generated for the above example would be named SpecificTestCase.test_something. To override that behaviour, you need to override the generate_cassette_name() method in your subclass.

If you are subclassing requests.Session in your application, then it follows that you will want to use that in your tests. To facilitate this, you can set the SESSION_CLASS attribute. To give a fuller example, let’s say you’re changing the default cassette name and you’re providing your own session class, your code might look like:

from betamax.fixtures import unittest

from myapi import session


class IntegrationTestCase(unittest.BetamaxTestCase):
    # Add the rest of the helper methods you want for your
    # integration tests
    SESSION_CLASS = session.MyApiSession

    def generate_cassette_name(self):
        classname = self.__class__.__name__
        method = self._testMethodName
        return 'integration_{0}_{1}'.format(classname, method)